One pearl necklace costs VND300,000 ($18) while another that looks nearly identical costs VND3 million ($180).

Market vendor Hong Dao said the latter was made of real Phu Quoc pearls, worth much more than the Chinese pearls used to make the cheaper necklace.

Khong Thi Thanh Truc, a partner in a Japanese-Vietnamese pearl company, said Phu Quoc pearls are 10 times more expensive than Chinese pearls.

Vo Van Doi, a pearl trader in An Thoi Town, said he had just sold a 12-millimeter pearl to a foreigner for VND15 million ($903).

Doi said it was not easy to find genuine Phu Quoc pearls because fakes have flooded the market.

He explained that fake pearls were easy to make but could be discovered by rubbing two pearls together.

Fake pearls would loose their enamel this way, he said.

Doi also said that putting a flame to pearls was an easy way to tell a fake as imitation pearls would shrink or be deformed by high heat.

But few shop owners would allow their pearls to be tested that way, he said.

A veteran trader on the island, Doi said the local pearl market is more complicated than ever as shops don’t provide credible evidence of the origins of their pearls.

And the fake pearls are everywhere, he said.

Even fishmongers and motorbike drivers often approach Doi with cheap fake pearls, asking him to sell them to tourists for a commission.

As an established trader, Doi said he always refuses such offers.

And it is not only fake pearls or Chinese imports that are hindering the island’s reputation, but even some Phu Quoc pearl companies now sell lower-quality freshwater pearls as opposed to those taken from seawater oysters.

Phu Quoc is located some 115 km off the coast of Rach Gia, capital of the Mekong Delta province of Kien Giang.